Ultra-fast and sensitive photo-induced phase switching in (EDO-TTF)2PF6

Organic conductor (EDO-TTF)2PF6 crystal having 14 filled band shows a metal (M)-insulator (I) transition accompanied with Peierls transition, charge ordering, and anion ordering at transition temperature, TC=280K. This crystal is an important and fascinating candidate for photo-induced M-I transition because the multi-instability will afford sensitivity to the tiny stimulation. We make the report of the reflectivity change in (EDO-TTF)2PF6 crystal induced by the irradiation of femto-second (fs) pulsed laser (pulse width: 120 fs, main wavelength: 800 nm, repetition rate: 1 kHz). The obtained results indicate that the highly efficient I-to-M transition occurs within 3 ps in this material. Based on these results, the strong electron-lattice cooperative interaction is proved to play an essential role in the driving process of this M-I transition. Also, 14 filled materials, which show M-I transition, accompanied with the charge ordering, can be classified as fascinating candidates not only for superconductivity but also for photo-induced cooperative phenomena and application in phase switching devices.